Hypodermic injector with adjustable impact plunger



A. VENDITTY Sept. 11, 1956 HYPODERMIC INJECTOR WITH ADJUSTABLE IMPACT PLUNGER 2 0 .5 mm. 5 5 m w 5 H m d. w 4 Q OW .l m 77 PM V \w/\\\V M m M mw Q 5 w m m V 1 1 Filed Sept. 7, 1954.

ited States Patent HYPODERMIC INJECTOR WITH ADJUSTABLE IMPACT PLUNGER Anthony Venditty, Detroit, Mich assignor to P. Scherer Corporation, Detroit, Mich, a corporation of Michigan Application September 7, 1954, Serial No. 454,446

4 Claims. (Cl. 128-173) This invention relates to a needleless hypodermic injector for injecting fluid into the human or animal body and relates more particularly to a compact, light-Weight instrument of simplified construction. It has been demonstrated that the most successful injectors of this type are those capable of discharging a minute stream or jet of liquid from an ampule at two different pressure stages sequentially. The initial high-pressure discharge causes the jet stream to distend the skin and force the liquid to a predetermined depth beneath the surface, depending upon the magnitude of the pressure. After the opening has been produced, the pressure of the stream is immediately reduced to a lower, second stage for completing transfer of the remainder of the liquid from the ampule. The two pressure stages are generally produced by a spring-actuated dual plunger assembly comprising a primary plunger of small diameter slidably mounted within a secondary plunger having a diameter equal to that of the flexible rubber-like follower or stopper within the bore of the ampule. The follower is cup-shaped and is adapted to expel liquid through the minute orifice in the end of the ampule as it advances down the bore. As the power springs expand, the primary plunger exerts a force against the central portion of the follower to distend that portion a short distance into the ampule and simultaneously eject a small amount of liquid from the orifice under high pressure. After the primary plunger has traveled to the end of its stroke, the secondary plunger engages the entire area of the bottom of the follower and moves the follower down the bore of the ampule to complete the injection at reduced pressure.

The instrument employed for the two-stage injection contains a plurality of springs, usually five, to provide the quick acting power of high magnitude required to produce high pressure discharge. This instrument is described in detail in the copending application of R. P. Scherer, Serial No. 170,101, filed June 24, 1950. I

The present invention is directed to a very small, compact instrument having considerably less space in the body thereof for power means. It is a primary object of the invention to provide such a small, compact instrument which has primary and secondary plungers capable of producing two diiferent pressure stages just like the prior instruments, but which employs power means of substantially less magnitude for propulsion of the plungers.

Another object is to provide an instrument in which the initial pressure stage is variable in magnitude by adjusting the impact force with which the primary plunger strikes the follower in the ampule.

A further object is the provision of novel compact means for storing and releasing the power required to propel the primary and secondary plungers.

These and other objects of the invention will become apparent from the following description and the accompanying drawings, in which:

Figure 1 is a longitudinal sectional view of the instrument of the invention.

Figure 2 is a section taken along the line 2-2 of Figure 1.

Figure 3 is a perspective view of the collet ring and one of the draw bars comprising part of the power means within the instrument.

Figure 4 is a perspective view of one of the collets comprising part of the power means of the instrument.

Figure 5 is a view similar to Figure l in which the plungers have been advanced to the point where all of the liquid has been expelled from the ampule.

Referring now to the details of the instrument, numeral 10 designates an elongated body, preferably cylindrical, having reamed portions 11 and 15 at either end which are threaded. shown in Figure 1, is fitted with holder 12 having a rough-surfaced nose 14. The nose may be coated with an abrasive or roughened in any suit able manner to prevent the instrument from slipping on the skin during an injection. The ampule 16 fits inside the ampule holder 12 and has a spherical nose terminating in a pointed end 17 provided with a minute discharge orifice through which liquid is expelled. A rubber follower 18, made from an oil resistant rubber, fits withinv the ampule to seal off the liquid contents from the air and to act as a piston for discharging the fluid from the ampule when pressure is applied thereto.

The opposite end of the body is fitted with a winding sleeve 30 adapted to rotate about a collet housing 36 which is screwed into the end 15 of the body 1%). The

adapted to lock with the flange of the collet so the ring and collet will rotate together. The collet flange and the ring may contain complementary notches for this purpose. The winding sleeve 30, the spacing sleeve 32 and the locking ring 34 are secured together by means of a pin 35 so that rotation of the winding sleeve 30 will turn the collet 40. The collet 40, rotatably mounted within the collet housing 36, comprises collet segments 40a (Figure 4) which are assembled alternately with draw bars 48.

An end bearing or end plug 20 is screwed into the lower threaded end 11 of the instrument. The bearing 20 serves as a support for the secondary plunger 60, which is slid-ably mounted in the central opening therein. One end of the secondary plunger 60 has a flange 63. The other end of the plunger 60 carries a sleeve 65 of enlarged diameter which prevents the plunger from mov ing inwardly past the bearing 20. In other words, the secondary plunger 60 can move only in a downward direction from the position shown in Figure 1. The height of the sleeve 65 is equal to the distance between the bearing 20 and the top of the follower 18 within the ampule. The sleeve 65 is adapted to slide within the bore of the ampule to advance the follower 18. A primary plunger 50, of smaller diameterthan the secondary plunger 60,. fits within the bore of the plunger 60 and is adapted to slide beyond the end thereof to distend the central area of the top of the follower 18 when force is applied thereto. The piston end of the plunger 50 is designated by the numeral 58 and is the portion which is adapted to slide within and engage the ampule follower. The primary plunger 50 has a spring seat 52 formed integrally therewith which slides axially within the body 10. The spring seat 52 has a boss 53 projecting therefrom which terminates in a long shaft 55, the outer end of which is threaded as The lower end of the instrument, as a removable ampule the secondary plunger spring Sli -within the upper end of the body 10, the top of the spring bearing against the collet housing 36. The threaded portion 56 of the primary plunger fits within the cpllet and draw bar assembly, which is best illustrated in Figures 3 and 4L One of the three collet sections 40 comprising the; collet 40 is illustrated in Figure 4 and has an outwardly extending flange 41 at one end and a tapered wall having internal threads 44 at the opposite end: The outer edge of the-threaded end terminates in a tapered surface 42. The collet segments 40a are assembled with draw bars 48 interposed therebetween, as best shown in Figure 2, the assembly forming a sleeve of circular cross section. The threads 44 of the colletare adapted to engage thethreads 56 on the end 5 5 ofthe primary plunger 50 when the collet is closed. The collet ring 46 normally surrounds the outer end of each ofthe collet segmentsso that the threads 44 are engaged with threads 56; The draw ring 46 may be moved back and forth axially by means of the draw bars 48 which have notches 47 that cooperate with the slots-45a in the ring to connect the draw bars with the ring. A release-button 7 0, which consists of a disc having a boss' projecting from the center thereof, fits within the end of the winding sleeve 30 with the boss inserted within the circle defined by the inner circumference of the draw bars and collets. A spring 71 normally forces the draw bars 48 away from the collet, as shown in Figure 1, said spring bearingagainst the outer surface of the collet flange 41 and the inner surface of the draw harflanges 49. In this position the collet ring 46 encircles the ends of the collets and draw bars. By means of the release button 70, atrial pressure may be applied to all three draw bars simultaneously, which causes the collet ring 46 to which the draw bars are connected to bepushedbeyond the end of the ellet 44). It will-be noted that the draw ring 46 has a tapered surface45 which is tapered at the same" angle as the terminating portion 42 of the collet. Thus, when; the draw ring" 46 ispushed downwardly, the surface 42- may slide past the surface 45 to permit thethreads 44 in the collet to disengage from-the' threads 56 in the end of the shaftSSL In operating the instrument the winding sleeve 30 is turned ina clockwise direction and thethreads 440p the collet; which are engaged with the threads 56 on the endofthe shaft 55, lift the primary plunger 50 until the'spring 59 has been fully compressed between the collet housing 36 and'the spring seat 52. Normally, the

colletsegments 40a are engaged with the shaft Sidne" to the action 'of' spring' 71 'Wiihi0 h keeps the draw raised; whichin turn causes the draw rin'g'46to m-erase the" rows-rend of "the oolle'tand force the threads 44" into engs emene with the-threads 56; When thespring is ran-y: compressed; an ampule 16*is placed Within the ampule holder lzwhich'is sbre'wed into theend o f inje'otori rhe-arapnle'he der" 12is screvv ed up m the point where the sleeve fis'jushengages the follower-'18::

lf le's's than the total content of the ampule is to"be' injected,- the ampule holder may be turned further into the instrument to predischar'ge any desired portion of rheiiquie'conrent's-or the ampule by causing the'sleeve 6S-to force meron w'er 18' down into the ampule? The volume of liquid discharged maybe shown by gradda tior'is msrkeaen body lfi and tlie holder 12:

The distance beta/cert the 1 primary" plunged 53 and the follower redesigned-es A'in'Figured canbe regulated by adjustrneiit o'f the"win'ding neat/ Whenthe spring is fully 'cornpi'iessedthe" distance between the primary plunger meme follower, a'nd thtis the impact withwhich" thefollower isptruok} is reatest?- It may be redrieedto' Y- Rd" point byrota'ting thef winding sleeve in coiinteihloek vi ise-"directlori until the rirrr a'ry' plunger" 5 7 provides no impact at an; Since" the" press-tr e at which the liquid" is discharg d engages the follouier "18, whi

depend upon rher'rce withwhich thepriniaryplun r ss 'sniis irre'nmpmerenewer1's;this resent-Emma" adjusted by regulating the distance A. The greater the impact or distance A, the greater the pressure at which the liquid is ejected. For intramuscular injections which are to go deep below the skin, maximum impact is desired. For subcutaneous injection, less impact is desired. The amount of impact may be made visible to the operator by providing complementary graduations on the winding" sleeve 30 and body 10 indicating the rotational position of the sleeve with respect to the body and, consequently, the axial position of the primary plunger 59. I

To release the energy in the compressed spring 59, the

'release button 70,is depressed against the force of the coil 71. This causes the draw bars 48 to move downwardly, thus sliding th draw ring 46 off of the end of the collet 40. The force of the spring 59 exerted against the seat 52 of the primary plunger 50 causes the threads 56 to slide out of the threads 44 in the co-llet, and the collet segments 40a are moved radially by this force so that they become recessed behind the inner surfaces of the draw bars. In this'way a clear opening is provided within the draw bars and the collet, and the primary plunger 58 is forced downwardly by expansion of the spring 59. The primary plunger is rapidly accelerated because it cariiesno load until it has traveled through the the follower 18a sharp blow, Care must be taken to keep the release button depressed until the spring has been fully released or else the threads will tend to reengage while the primary plunger is in motion.

The primary plunger 58 will distend the central portionof the follower r1810 eject liquid at high pressure until the spring seat 52' engages the flange 63 of the secondary plunger 60. At this point both the primary plunger and thesecondary plunger descend together until the ampule follower has been forced intothe end of the ampule and all of-the liquid contents discharged therefrom, as illustrated in' Figure 5:

When the injection has been completed, the release button is permitted to assume its normal position where'- upon th'etlraw ring'46 slides 'over the ends of the collet to'on'ce again engage the threads thereof with the threads" 56in the end of theshaftii The Winding sleeve 30 is then turnedin aclOc'kWis-dirction once again to compress'" the springand cause primary plunger 50 to beprimary and secondary plungers. Furthermore, because thedist'ancebetwen the'primary plunger and the ampule follower is variable, the pressure at which the liquid is discharged during the primary state is fully adjustable. Subsequently, when the secondary plunger engages the follower, the pressure is reduced by reason of the fact that the area is increased without'any increase in the forte imposed by the spring.

Various modificationsin thestructure of the instrument will occur to those skilled in the art without departing fron'i 'th'e sp'irit and scope of'the invention. It is, therefore, not my intention to limit'the invention to the forms illustrated other-than as necessitated by the scope of the appended claims."

I claim as my'irivention": I U lpl'ira hypodermieinjector, an assembly comprising art-elongated body, an' ampule holder detachably con-f nected to one end thereof and adapted to'hold an orificed am'piile ha ing liquid and a follower in thebore thereof, primary and secondary plungers mounted within said body for engaging and propelling said follower to discharge liquid from said ampule at two different sequential pressures, said primary plunger being associated with power means within said body and adapted to propel the secondary plunger after traveling an initial distance, said primary plunger being adjustable with respect to said follower to permit varying the distance therebetween, thus varying the force of impact imposed upon the follower by the primary plunger, said power means comprising a coil spring interposed between the end of said body and said plunger head, a screw disposed within said spring and fixed to said head for compressing the spring, latch means manually rotatable within said body and having threads adapted to engage the threads of said screw to constrain it against axial movement and to disengage the threads of said screw to suddenly release the energy of the spring.

2. In a hypodermic injector, an assembly comprising an elongated body, an ampule holder detachably connected to one end thereof and adapted to hold an orificcd ampule having liquid and a follower in the bore thereof, a plunger slidably mounted within the body and adapted to engage and propel said follower to discharge said liquid from the ampule, said plunger having a head associated with power means within said body for propelling said plunger, said power means comprising a coil spring interposed between the end of said body and said plunger head, a screw disposed within said spring and fixed to said head for compressing the spring, latch means manually rotatable within said body and having threads adapted to engage the threads of said screw to constrain the screw 6 against axial movement and to disengage the threads of said screw to suddenly release the energy in the spring.

3. The injector of claim 2 wherein said latch means comprises an internally threaded collet having a plurality of segments surrounding said screw, a draw ring adapted to embrace said segments to bring them into engagement with said screw threads, draw bars disposed between said segments for actuating said draw ring, and means accessible from outside said body for actuating said draw bars to release said spring.

4. The injector of claim 2 wherein said latch means comprises an internally threaded collet having a plurality of segments surrounding said screw, said collet having a radial flange at the upper end thereof, a draw ring adapted to embrace said segments to bring them into engagement with said screw threads, draw bars disposed between said segments having the lower ends thereof connected to said draw ring and terminating at their upper ends in radially extending flanges, means engaging said upper ends for actuating said draw bars to move said ring from the collet and permit the collet threads to disengage the screw threads, and compressible means disposed between said collet flange and said draw bar flanges adapted normally to hold the draw ring in collet-embracing position.

References Cited in the file of this patent UNITED STATES PATENTS 

